Made by the action of sulphuric acid on borax, or by purification of native boric acid, which is a compound of the element boron with oxygen, and is obtained from certain mineral springs in Italy. White, pearly, glistening crystals, soluble in 25 parts of cold and 3 parts of hot water. The saturated solution has a strength of 4 per cent.

Physiological Actions

Boric acid is antiseptic, disinfectant, and deodorant, destroying low organisms, and stopping fermentation and putrefactive changes.

It is not irritating externally, but rather the reverse, and when applied to wounds prevents suppuration. Internally, in large doses, it is a gastro-intestinal irritant, and poisoning has been caused by washing out internal cavities with a 5 per cent. solution. The symptoms were: nausea, vomiting, hiccough, disturbed respirations, rapid; feeble pulse; erythema and ecchy-mosis, subnormal temperature, and collapse. As a wash for babies' eyes and mouths, the saturated solution is diluted one half with water.

It is used as the basis of a variety of mouth washes for the sick. It constitutes the largest part of Thiersch powder, used in making an antiseptic solution. (See salicylic acid.) Its use as a preservative for milk is dangerous, the milk so preserved being injurious, especially to infants.

Unguentum Acidi Borici. Ointment Of Boric Acid

Contains paraffin, white petrolatum, and boric acid.